Focus of the chapter:
- Why primates evolved
- The first true primates
- Eocene euprimates
- Origins of apes and New World monkeys
The arboreal hypothesis explains primate origins in terms of adaptation to tree living. Other hypotheses focus on vision (visual predation hypothesis) or food resource exploitation (angiosperm radiation hypothesis).
The earliest primates most likely evolved in the Cenozoic; scientists debate about exactly when this happened. Paleocene primates are known as plesiadapiforms; other Eocene primates are the adapids and omomyids.
During the Eocene, basal anthropoids evolved; it is these forms that likely gave rise to later primates such as those found in the Fayum: oligopithecids, parapithecids, and propliopithecids.
New World monkey origins have long been debated; at least four different hypotheses exist to explain their evolution. Most likely, the ancestors of modern New World monkeys migrated from Africa to South America.
Ape origins are found in the proconsulids, a diverse group of primates from the Miocene. Ape ancestors have been found in Africa, Asia, and Europe.